CHAPTER 3 FEATURES OF ORGANIC MANURES 3.1 Manure Plants need a well balanced diet, for better growth and yield. Manures are the substances which provide nutrients for proper growth of plants. Manure is anything that has been added to the soil to increase its fertility and enhancing for plant growth (Boller and Hani, 2004). The word manure came from Middle English "manuren" meaning "to cultivate land," and initially from French "main-oeuvre" = "hand work" alluding to the work which involved manuring land. Manure is not just the urine and faeces from livestock, but also the bedding, runoff, spilled feed, parlor wash, and anything else mixed with it. Manure contributes to soil fertility and tilth. In addition to nutrients, manure provides carbon and other constituents that affect soil humus content, biological activity, and soil physical structure (Wagner and George, 2004). Manures contribute to the fertility of the soil due to addition of organic matter and nutrients, such as nitrogen that is trapped by bacteria in the soil (Haynes, 2003). 55
3.2 Classification of manure Manures can be divided into two classes: Organic or Inorganic. Organic manures are derived from decaying material of plant or animal origin. Inorganic manures, also known as fertilizer, are derived from chemical processes, that are most often man-made. Organic manures often provide more than one of the many substances needed by plants for their growth. Inorganic manures usually provide only one of the many substances needed by plants for their growth (Boller and Hani, 2004). 3.2.1 Organic manures Almost any kind of organic matter may be used as manure, but some kinds are better than others. Organic manures vary widely in the amount of plant nutrients that they contain. Some are more concentrated than others. Compost is one of the less concentrated organic manures, but it is extremely valuable in adding extra body to soils especially the sandy soils. Organic manures which break down or decay quickly are available to the plant faster than those which decay slowly (Boller and Hani, 2004). In these study four types of manures namely Seaweed, Cow dung, VermiCompost and Coir waste were used (Fig 3.1). 56
SEAWEED COW DUNG VERMI COMPOST COIR WASTE Figure 3.1 Types of Organic Manure 3.2.2 Inorganic or Artificial manures These manures, or fertilizers, are either of mineral origin or manmade through chemical processes. Because these fertilizers are relatively simple in structure, they break down and are available to plants rather quickly. Fertilizers are available as 'Complete Fertilizers' with varying degrees of chemical compositions or as individual chemicals such as Nitrogen, Phosphorous or Potash. In either case the fertilizers are also available as timed release or quick acting. Artificial manures are often more 57
expensive than organic fertilizers, but tend to be easier to use, less odorous and may be stored longer without deteriorating (Boller and Hani, 2004). Green manure Soil productivity is an important concern for farmers. Green manuring is gaining popularity as a method that successfully improves soil productivity (Haynes, 2004). The addition of peat moss material improves soil tilth. At the same time, the nutrients used in plant growth are conserved and returned to the soil to enhance its fertility (Boller and Hani, 2004). Leguminous crops, such as clover, when used as green manure also fix nitrogen through rhizobium harboured in their root nodules (Whitmore, 2000). Green manure approaches to crop production may improve economic viability, while reducing the environmental impacts of agriculture (Cherry et al., 2006). Animal manure Most animal manure is faeces excrement (variously called "droppings" or "crap" etc) of herbivores and poultry or plant material (often straw) which has been used as bedding for animals and thus is heavily contaminated with their faeces and urine (Whitmore, 2000). The Vermicompost manures may be used by mixing earthworm with soil or by adding them to compost. Cow dung is a good source of nitrogen and phosphorus. Seaweed with amino acids is an excellent source of calcium and potash (Boller and Hani, 2004). 58
Fertilizers Fertilizers quickly break down to provide specific nutritional needs to plants. Urea is another good source of Nitrogen, but once again, must be used carefully as it will promote an excess of green growth and make plants weak, spindly and susceptible to disease. Potassium is an essential element deficient in sandy soils. Calcium is another essential element for most plants. Also known as lime, it helps to neutralize the acidity of acidic soils and allows the release of plant nutrients that would otherwise be bound in the soil and unavailable to plants. Lime should be applied carefully as it may cause a deficiency of other elements in plants if used in large quantities. Superphosphate, Nitro-chalk, Rock phosphate, Calcium cyanamide, Ammonium sulfate, Ammonium nitrate and Magnesium phosphate are the different examples of fertilizers (Boller and Hani, 2004). 3.3 Forms of available nitrogen in manures As Figure 3.2 indicates about half of the nitrogen in manure is in the form of ammonium and about half is in the form of organic material. Microbes that consume the organic compounds excrete ammonium. One of the four things will happen to the ammonium - regardless of whether it comes directly from the manure or from microbes consuming the organic compounds. The ammonium may either be used by plants immediately, converted to ammonia and lost to the air or converted to nitrate which will be used by plants or microbes. The "immobilized" nutrients become available to plants when the microbes are consumed by other organisms that release ammonium as a waste product. In the warmth of summer, plants and microbes 59
grow more vigorously and use ammonium and nitrate quickly. Losses of nitrate to leaching are greater in spring and autumn when fewer plants and microbes can turn it into organic matter (Wagner and Georg 2004). Figure 3.2 Forms of available nitrogen in manure 3.4 Physical and chemical properties of soil nutrients Plants need only 16 nutrients for good growth. It must be provided either by the soil or by animal manure or mineral fertilizer. Some other mineral nutrient elements, e.g. Na, Si, Co, have a beneficial effect on some plants but are not essential. About 13 essential mineral nutrients are required for growth (Mc Lean, 1987) 60
Macronutrients a) Major nutrients present in fertilizers for almost use in all crops on most soils: N = nitrogen (taken up as NO 3- or NH 4+ ) P = phosphorus (taken up as H 2 PO4 - etc.) K = potassium (taken up as K + ) b) Secondary nutrients are added to fertilizers mainly for use in certain crops on some soils: 2 S = sulphur (taken up as SO - 4 ) Ca = calcium (taken up as Ca 2+ ) Mg = magnesium (taken up as Mg 2+ ) c) Micronutrients of which the critical contents in plants are 0.3-50 mg/kg of dry matter: Heavy metals like iron, manganese, zinc, molybdenum and copper (Fe, Mn, Zn, Mo, Cu taken up as divalent cation or chelate) and non metals like chlorine and boron. d) Beneficial nutrients like sodium (taken up as Na + ; can partly replace K + for some crops), silicon (taken up as silicate, etc., for strengthening cereal stems to resist lodging), cobalt (mainly for N-fixation of legumes) and chlorine (useful for some crops in greater than essential amounts, for osmotic regulation and improved resistance to some fungi). 61
Components of soil fertility (Lory and Russelle, 2005) Soil depth (determines the volume of soil accessible to the root system). Soil structure (size distribution and aggregation of particles). Soil reaction (an indicator and regulator of chemical processes and equilibria). Content of nutrients in different degrees of availability. Storage capacity for soluble nutrients from the soil and fertilizers. Humus content and quality (including proportion in mineralizable form). Quantity and activity of soil organisms as agents of transformation processes. Features of high fertile soil Mobilizes soil nutrients from the reserves. Stores water soluble nutrients in available forms. Offers a balanced nutrient supply due to its self regulatory system. Maintains good soil aeration for the oxygen requirements of roots. 62
There are alternative ways of making use of soil fertility in farming: Exploitation i.e. farming without any added fertilizer (e.g. in shifting cultivation). Utilization of as many components of soil fertility as possible without compensation and yet without negative yield effects (e.g. by applying only moderate amounts of fertilizer N and P). Maintenance and improvement of soil fertility to assure consistent high yields (e.g. by compensating for losses due to removal and by soil amendments to improve fertility). Physical parameters of soil 3.4.1 Estimation of soil ph The ph of the soil suspension was estimated using a ph meter. 3.4.2 Determination of bulk density of the soil sample The soil sample was dried in a hot-air oven at 105 C and its dry weight was recorded. The procedure was repeated three times till a constant weight was achieved. The dried soil sample was transferred into a 100ml measuring cylinder and the volume was measured. The bulk density was calculated using the formula. Bulk density (g/m 3 ) = Weight of the soil (g)/ Volume of the soil (cm 3 ) 63
3.4.3 Determination of specific gravity of soil sample The soil sample was homogenized and dried in a hot air oven at 105 C. This was repeated until a constant weight was achieved. Two widemouthed glass bottles were taken and their initial weight was recorded. The dried soil sample was transferred to a fixed volume in a bottle and was filled in bottle distilled water to the same volume. The weight of both the bottles with soil and distilled water was measured. The specific gravity of soil was calculated as shown below. Specific gravity of soil y y z z 1 1 where y = Final weight of bottle with soil y 1 = Initial weight of bottle used for soil z = Final weight of bottle with distilled water z 1 = Initial weight of bottle used for water 3.4.4 Determination of moisture content of soil sample The homogenized soil sample was dried in a hot air oven at 105 C till a constant weight (I) was achieved and cooled in a desiccator to record its final weight (F). The moisture content of the sample was calculated as follows. Moisture content (%) of the soil sample (I F) 100 I where I = Initial weight of the sample (in g) F = Final weight of the sample (in g) 64
3.4.5 Determination of the water holding capacity (WHC) of soil sample For WHC determination, bottom-perforated rounded soil boxes of about 5.6 cm and 1.6 cm diameter were used. The initial weights of the empty box were recorded. The soil sample was homogenized by drying it at 105 C. A filter paper (preferably Whatman No.1) was kept above the perforated bottom of the soil box. The box was filled with dried soil and its final weight (F 1 ) was recorded. The soil box was placed in a petri dish containing water and the whole set-up was left undisturbed for about 12 hrs. This allowed the water in the petri dish to enter into the oil box and ultimately to saturate it. The box was dried on the outside before weighing. The WHC was calculated as follows. WHC (%) (F2 F 1) (F1I) 100 (F I) 1 where I = Initial weight of soil box (g) F 1 = Final weight of soil box with soil (g) F 2 = Final weight of the soil box with water-saturated soil (g). 65
Chemical parameters of soil 3.4.6 Determination of total nitrogen in soil sample Reagents a. Catalyst mixture: 20 g of copper sulphate 3 g of mercuric oxide and 1 g of selenium powder. b. Concentrated sulphuric acid. c. Sodium hydroxide (40%) d. Zinc granules e. Boric acid indicator solution (4%) f. Hydrochloric acid (0.1N) Methodology 10 g of soil sample was taken into a clean dry kjeldahl flask and 20 g of catalyst mixture was added.the contents were mixed well and left for 20 min. 35 ml of sulphuric acid was added to the flask, mixed well and left it for another 15 minutes. The content was digested over the Bunsen burner for about 2 hr and was cooled 100 ml of distilled water was added. Then it was distilled with 100 ml of sodium hydroxide solution and a few zinc granules in a distillation flask. 25 ml of boric acid cum indicator solution was pipeted out in a 500 ml Erlenmeyer flask and keeping its delivery end below the condenser of the distillation flask. Collection of distillate in the flask was confirmed by titrating it against 0.1N Hydrochloric acid using an indicator. Color change from blue to light brown to pink was the end point. 66
Calculation Total Nitrogen (mg / g) (V1V 2) N 14 S Percent total nitrogen (V1V 2) N1.4 S where V 1 = Volume of titrant used against sample (ml) V 2 = Volume of titrant used against blank (ml) N = Normality of titrant (0.1) S = Weight of soil used (g) 3.4.7 Determination of total phosphorus content of the soil sample Reagents a. Ammonium molybdate solution (6%) b. Stannous chloride solution (0.1N) c. Concentrated nitric acid d. Concentrated perchloric acid e. Sulphuric acid solution Methodology The acid-dried soil sample was dried to a fine powder and weighed 0.5 g of it was weighed in round-bottomed flask.2 ml each of concentrated nitric and perchloric acid were added to the soil sample. The flask in a hot 67
plate was heated till the content became dry. Then 2 ml of sulphuric acid was added and heated for 15 min. The digested content was filtered through Whatman No.44 filter paper the filtrate was made up to 250 ml with distilled water. The phosphorus content of the filtrate was determined by adding 4 ml of ammonium molybdate solution. Calculation Total Phosphorus (ppm) P1 V 1000 W where P 1 = PO 4 P in digested content (mg/l) V = W = Total volume in solution (ml) Weight of soil sample 3.4.8 Estimation of calcium in soil sample Reagents a. Solid ammonium chloride b. Potassium permanganate (0.1N) c. Silver nitrate Methodology 50 ml of the hydrochloric acid extract was taken in a 500 ml beaker and 2 g of solid ammonium chloride and a piece of red litmus paper was added to indicate the ph of the beaker content. The content of the flask was 68
boiled with 10 ml of saturated ammonium oxalate. After this, the beaker was undisturbed for another 5 min. An ammonium oxalate can be added until no more precipitate was formed and then filtered through a filter paper (Whatman No. 40). The filtrate was collected in the conical flask and added 10 ml of dilute sulphuric acid was added and heated in a hot plate at 70 C for 3 min and the supernatant was titrated against 0.1N potassium permanganate. The end point was the appearance of faint-pink color. The calcium content of soil sample was determined. Calculation Amount of calcium in 100 g of soil on moisture free basis (%) 0.02 (250/50) (500/50) (100/W) (100/(100 M) where W = Weight of soil taken M = Moisture percent of soil. 3.4.9 Determination of sodium and potassium in soil sample Reagents a. Ammonium acetate solution (1N) b. Standard potassium chloride solution (1mg/100ml) Methodology 5 g of soil was taken in an Erlenmeyer flask containing 5 ml of ammonium acetate. The flask was placed on a rotatory shaker and rotated for 69
5 min. The content of the flask was filtered through Whatman filter paper No.1 and the filtrate (25ml) was collected. After setting, the potassium filter initiated the compressor and lighted the burner of the instrument. The air pressure was set at 5 lbs using gas feeder to produce sharp flame cones. Using highest potassium standard solution, the instrument was adjusted to show full reading. Similarly using extract solution, the zero reading was set. The above procedure was repeated for sodium filter also. A standard curve was drawn by plotting the reading of standard against their concentration. From the calibration curve, the concentration of potassium and sodium in the solution were calculated. Calculation av Amount of available K (Cmol / kg) 2.24 W where a = concentration of K /Na in the unknown sample read from the calibration curve V = Volume of extract (25 ml) W = Weight of soil (g) 3.4.10 Determination of manganese content of the soil sample Reagents a. Manganese stock solution (1mg/100ml) b. Special reagent: Concentrated nitric acid (2:1), 37.5 g of mercuric sulphate, 85% phosphoric acid and 17.5 mg of silver 70
nitrate. The volume was made up to 500 ml using distilled water after stirring the contents well. c. Ammonium persulphate crystals. Methodology Different aliquots of working solution were taken in a series of beakers and the volume was made up to 100 ml using distilled water. 100 ml of distilled water was taken as blank. Similarly 100 ml of sample was pipetted out in a beaker. To all the beakers, 5 ml of special reagent was added and heated. 1 g of ammonium persulphate was added to each beaker and boiled for two min. The color was measured in a spectrophotometer at 545 nm. 3.4.11 Determination of magnesium in soil sample Reagents a. Solid ammonium chloride b. Diluted ammonium hydroxide (1:4, 1:7) c. Disodium phosphate and silver nitrate Methodology 1 g of solid ammonium chloride and ammonium hydroxide solution (1:4) were added in small quantities till red litmus paper turned blue and added10 ml of disodium phosphate solution was added to it.this was kept for about 12 hr and the precipitate was filtered through Whatman No.42 filter paper.the precipitate was washed with diluted ammonia. The precipitate was 71
placed in a silica crucible and dried in a hot-air oven at 105 C. The dried precipitate was made to a white ash powder by heating the crucible for 30 min in a red hot flame and the final weight of the crucible was determined. Calculation Amount of magnesium in 100 g of soil on a moisture free basis (%) 48 250 500 100 100 (b a) 222 50 50 W 100 W where b = Weight of silica crucible + Mg 2 P 2 O 7 precipitate a = Weight of silica W = Weight content of the soil box 3.5 Results and Discussion The physical and chemical characteristics of soil at the experimental site using coir waste manure were taken into to analysis. Physical characteristics such as ph, sand, silt, clay, specific gravity, bulk density, moisture content and water holding capacity of the soil were measured. Further chemical characteristics such as nitrogen, phosphorus, potassium, calcium, sodium, magnesium, manganese and organic carbon content of soil were measured and analyzed. Soil samples were collected from before planting and after harvesting of black gram. 72
Table 3.1 Physical characteristics of soil at the experimental site Period of sampling Treatments ph Sand (%) Silt (%) Clay (%) Before Planting Soil Sample 4.10 70.2 4.4 25.4 After Harvesting Control 4.07 69.8 5.3 24.9 Coir waste treated Anabaenaa azollae 5.40 68.7 6.0 24.5 Coir waste treated Phormidium 4.98 68.0 5.8 24.2 Coir waste treated Oscillatoria 4.11 70.00 5.2 25.1 Table 3.2 Physical characteristics of soil at the experimental site Period of sampling Before Planting After Harvesting Treatments Soil Sample Specific Gravity (mg/m 3 ) Bulk Density (g/cm 3 ) Moisture Content (%) Water holding capacity (%) 2.64 0.4 48.2 52 Control 2.62 0.5 50.4 56 Coir waste treated Anabaena azollae Coir waste treated Phormidium Coir waste treated Oscillatoria 2.74 0.8 85.3 74 2.64 0.6 76.5 71 2.58 0.5 67.3 68 Tables 3.1 indicates an increase in ph content of soil after harvest of plant using treated coir waste in the order of Anabaena azollae sp > Phormidium sp > Oscillatoria sp. Application of organic manure increased the ph of the soil after harvest. This agreed with the findings of Mulongoy (2003). The maximum reduction of sand and clay in the soil was observed in coir waste treated Phorimidium sp after harvest of plant. It was supported with Bill (2001), who observed high reduction of sand and clay content of soil, after harvesting of black gram using organic manure. 73
The silt content of soil was gradually increased in Anabaena azollae treated coir waste manure when compared with other treatments and untreated soil. The bulk density of soil was gradually increased in coir waste manures treated soil (Table 3.2) when compared with control. This is supported by the work done by Sangakkara (2000), who observed that organic manure increases the bulk density of soil. The moisture and specific gravity were found to be higher in soil of Anabaena azollae treated coir waste manure when compared with other treatments. The water holding capacity of soil was increased in the preposition of plant using (coir waste + Anabaena azollae manure) > (Coir waste + Phormidium) > (Coir waste + Oscillatoria). This result was in accordance with the findings of Higas (2004), that organic manure enhances the water holding capacity of soil, plant vigour and soil properties. Table 3.3 Chemical properties of soil at the experimental site Period of sampling Treatments N (%) P (ppm) K (cmol/kg) Ca (cmol/kg) Before Planting Soil Sample 0.085 6.7 0.07 0.62 After Harvesting Control 0.83 4.4 0.02 0.57 Coir waste treated Anabaena azollae Coir waste treated Phormidium Coir waste treated Oscillatoria 0.230 6.9 0.05 0.65 0.215 6.4 0.04 0.61 0.080 4.6 0.02 0.54 74
Table 3.4 Chemical properties of soil at the experimental site Period of sampling Before Planting After Harvesting Treatments Soil Sample Na (cmol/kg) Mg (cmol/kg) Mn (ppm) Organic carbon (%) 0.30 0.25 4.94 0.79 Control 0.10 0.20 4.30 0.82 Coir waste treated Anabaena azollae Coir waste treated Phormidium Coir waste treated Oscillatoria 0.30 0.30 3.47 1.02 0.27 0.24 4.06 0.91 0.08 0.18 4.14 0.80 Table 3.3 describes the chemical properties of soil before planting and after harvesting of plant. Coir waste treated with Anabaena azollae and phormidium showed a significant increase N 2 content without any significant change in the P, K and Ca content. There was no significant change in N, P, K and Ca content in coir waste treated with Oscillatoria. Artificial /chemical fertilizers like urea provides N, P, K constituents to the soil. But imbalanced use of chemical fertilizers on soil is not only harmful to microflora and fauna but also reduce the progressive productivity potential of land. The micronutrients such as sodium, magnesium and maganese present in the soil showed no significant increase in coir waste treated with cyanobacteria (Table 3.4). This was supported by Maynard (2001) in which cow dung manure and poultry manures were more effective in amending the soil by improving the N, P, K levels and micronutrients of the soil. 75
The physical and chemical experimental site before planting and after harvest of a plant using three different cyanobacteria treated coir waste manures were discussed. Among the three species, Anabaena azollae treated coir waste manure showed best organic manure activity on the soil (Table 3.1 and 3.4). This was supported by Bill (2001) who observed that organic manure improves soil tilth, infiltration rate and soil water holding capacity contributing to increased nutrient uptake by the crop being an important source of raw or partially decomposed organic matter. Phormidium sp treated coir waste manure showed 76% of improvement of soil properties. But Oscillatoria treated coir waste manure did not interact with soil. The physical and chemical properties of soil were on par with the control (Untreated) and before planting soil. Thus from the above results, Anabaena azollae treated manure was selected for the growth of black gram plants. 76